JPH04212706A - Magnetic head - Google Patents

Abstract

PURPOSE:To eliminate the trouble of a pseudo gap and to improve reproduced output in a parallel type MIG head. CONSTITUTION:Ferromagnetic metallic thin films 9a and 9b are formed on the gap formed surface of at least either of a pair of magnetic core half bodies 1a and 1b made of monocrystal ferrite through a heat resistant thin film, and this ferromagnetic metallic thin film is butted with the other magnetic core half body through a non-magnetic material which becomes a magnetic gap 2, so that a magnetic head is obtained. The crystal surface of the main magnetic path constituted surfaces 103a and 103b of the magnetic core half body where the ferromagnetic metallic thin film is formed is made about {110} and an angle theta formed by vector A which is parallel with crystal axis <100> on the magnetic path constituted surface and turns in a direction where it goes away from the gap formed surface with vector B which is parallel with the intersecting line of the main magnetic path constituted surface with the gap formed surface and approaches to a recording medium opposed surface is set within 0-10 deg. or 80-180 deg..

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head used in high-density magnetic recording and reproducing devices such as VTRs (video tape recorders), DATs (digital audio tape recorders), and HDDs (hard disk drives).

0002

[Background Art] In recent years, in magnetic recording and reproducing devices such as VTRs and DATs, improvements in temporal recording density (higher frequency band) and spatial recording density (narrower tracks, shorter wavelengths) is in progress.

[0003] Focusing on the shortening of the wavelength,
In order to perform short-wavelength magnetic recording, it is desirable to use magnetic media with high coercive force, and magnetic heads for such media usually have high frequency characteristics and wear resistance of the magnetic core, as well as magnetic flux concentration during recording. A property is required that the area near the gap where the magnetic field is formed is unlikely to be magnetically saturated.

[0004] As shown in FIG. 4, a magnetic head that satisfies these requirements has a pair of magnetic core halves 1a and 1b made of a ferromagnetic oxide with excellent high frequency characteristics, such as Mn--Zn ferrite, which is non-magnetic. Ferromagnetic metal thin films 3a and 3b, such as sendust, having a high saturation magnetic flux density are formed near the magnetic gap 2 formed by abutting materials. Note that the magnetic core halves 1a and 1b are joined by a glass 4. 5 is a winding groove.

The boundary surfaces 6a and 6b between the ferromagnetic oxide and the ferromagnetic metal thin films 3a and 3b as described above form the magnetic gap 2.
The so-called parallel type MIG (Metal in
In the case of a composite magnetic head with a Gap) structure, the boundary surface 6
a and 6b act as pseudo gaps, and the frequency characteristic curve of the recording/reproduction output exhibits a waviness phenomenon as shown in FIG. 5, causing a problem of deterioration of the S/N ratio.

[0006] As a solution to this pseudo gap problem,
JP 01-133204 G11B 5/127
In the publication (hereinafter referred to as the first reference), the magnetic core half 1
After exposing the perfect crystal plane by performing treatments such as mirror polishing, phosphoric acid etching, and reverse sputtering on the magnetic gap 2 forming surfaces of a and 1b, the heat resistance is 1 nm or more and 1/10 or less of the gap length. It is disclosed that ferromagnetic metal thin films 3a and 3b are formed via thin films 7a and 7b (see FIG. 6).

Furthermore, in the first cited example, when single crystal ferrite is used as the ferromagnetic oxide core material, the effect of the above-mentioned means for solving the pseudo gap problem depends on the crystal orientation of the ferrite core, and the magnetic gap formation {1} compared to the case where the plane is the {111} crystal plane of the ferrite single crystal.
00} crystal plane is more advantageous, but various combinations of the crystal orientations of the gap forming plane and the main magnetic path forming plane can be considered, and this crystal orientation is suitable for parallel type MIG heads. It is not easy to predict how this will affect the relationship between the recording/reproducing output and the pseudo-gap output, and there are still few experimental reports.

On the other hand, Japanese Patent Application Laid-Open No. 02-98803 G11
According to the publication B 5/127 (hereinafter referred to as the second reference), regarding the recording and reproducing output in a parallel type MIG head using single crystal ferrite as the ferromagnetic oxide core material, ferrite cores as magnetic head core halves 1a and 1b are used. It is stated that by setting the crystal orientation of the ferromagnetic metal thin film part in a direction with low magnetic permeability, the magnetic permeability of the ferromagnetic metal thin film part increases, and the recording and reproducing characteristics of the magnetic head as a whole improve. This relates to a magnetic head in which ferromagnetic metal thin films 8a and 8b independently constitute a magnetic path that goes around the winding groove 5, as shown in FIG. 7(b). This does not necessarily apply to a magnetic head in which the ferromagnetic metal thin films 9a and 9b are removed within the winding groove 5, that is, the ferromagnetic metal thin films 9a and 9b do not constitute a magnetic path that goes around the winding groove 5 alone.

[0009]

Problems to be Solved by the Invention The present invention aims to solve the above-mentioned pseudo-gap problem and improve the recording and reproducing output in the parallel type MIG head, and in particular uses single crystal ferrite as a ferromagnetic oxide core material of the magnetic head. Assuming that it is used, the crystal orientation of the single crystal ferrite part is more suitable than the combination of main magnetic path forming plane {110} and gap forming plane {100} recommended in the first reference cited above. reveal.

0010

[Means for Solving the Problems] The present invention provides a method for forming a ferromagnetic metal thin film on the gap forming surface of at least one of a pair of magnetic core halves made of single-crystal ferrite via a heat-resistant thin film. In a magnetic head in which the ferromagnetic metal thin film and the other magnetic core half are butted together with a non-magnetic material interposed therebetween to form a magnetic gap, the main magnet of the magnetic core half on which the ferromagnetic metal thin film is formed is The crystal plane of the path configuration plane is approximately {110}, and <100> in the main magnetic path configuration plane
The angle θ formed by the vector parallel to the crystal axis and moving away from the gap forming surface and the vector parallel to the intersection line of the main magnetic path forming surface and the gap forming surface and approaching the recording medium facing surface is 0° to 10°. Or within the range of 80° to 180°.

[0011]

[Operation] In the magnetic head configured as described above, the magnetic path forming plane of the ferrite core portion is approximately {110}, and all of the main symmetry axes <100>, <110>, and <111> of the cubic system are Since it exists in the main magnetic path configuration plane, it is expected that the symmetry and anisotropy of the magnetic properties can be effectively utilized. In order to solve the problem of pseudo-gap and improve the recording/reproduction output in a parallel MIG head having a ferrite core, at least the main magnetic path configuration plane recommended in the first reference is the {110} plane, and the gap The forming surface is {
It has been experimentally found that this head has an effect that is equivalent or superior to that of a parallel type MIG head with a 100} plane.

0012

EXAMPLES The details of the experiments that led to the invention will now be explained in detail with reference to tables and drawings. The inventor of the present application has proposed that the ferromagnetic oxide core portions as the magnetic core halves 1a and 1b are composed of single crystal ferrite having various crystal orientations as shown in Table 1, and that A parallel type MIG head having an appearance and cross-sectional shape as shown in FIG.
The measurement results shown in Table 3 regarding the recording and reproducing output were obtained.

[0013]

[Table 1]

[0014]

[Table 2]

[0015]

[Table 3]

[0016] Processing conditions for the gap forming surface in Table 2,
The conditions for forming the heat-resistant thin film are in accordance with the means for solving the pseudo gap problem disclosed in the first reference. In Table 1, the meanings of the words "main magnetic path forming surface," gap forming surface, and "recording medium facing surface" are in accordance with the conventions of those skilled in the art, and correspond to surfaces 103, 101, and 102 in FIG. 6, respectively, but they will be explained in more detail. Then, the gap forming surface 101 means a surface parallel to the surface where the ferromagnetic metal thin film is brought into contact with the other magnetic core half via a nonmagnetic material in the MIG head that is the object of the present invention, and is Road configuration surface 103
means a plane that includes the shortest magnetic path around the winding groove 5 of the magnetic head and is perpendicular to the gap forming surface 101;
The recording medium facing surface 102 means a surface perpendicular to the gap forming surface 101 and perpendicular to the main magnetic path forming surface 103. Furthermore, since the main magnetic path forming surface 103, the gap forming surface 101, and the recording medium facing surface 102 are surfaces that are orthogonal to each other, if the crystal orientation of any two surfaces is determined, the crystal orientation of the other one surface will inevitably be determined. It's decided.

[0017] In Table 1, ■ is the crystal orientation recommended in the first reference, and serves as a standard comparative example for the present invention. ■ and ■ in Table 1 are the embodiments disclosed in the first citation, but from the perspective of whether the effect of the pseudo gap problem solving means can be expected, they are considered to be less preferable than the above ■. This is the crystal orientation.

Although the first reference does not distinguish between ■ and In the combination where is the {111} crystal plane, the asymmetry of the magnetic path within the main magnetic path constituting plane 103 and the {100}
Reflecting the asymmetry of the crystal axes in the plane, two types of non-equivalent combinations can be considered. A vector A in the {110} crystal plane that is parallel to the <100> crystal axis and directed away from the gap forming plane, and the main magnetic path forming plane 103a, 1
Assuming that a vector B is parallel to the line of intersection between 03b and the gap forming surface and approaches the surface facing the recording medium, the value of the angle θ formed by both vectors A and B is used.

[0019] ■, ■, ■ in Table 1 correspond to the above ■, ■, ■
The combination of the crystal orientations of the gap-forming surface and the surface facing the recording medium in (2) is switched, and the distinction between (1) and (2) is based on the same concept as the distinction between (2) and (2) above. The measurements of F characteristic waviness and recording/reproducing output in Table 3 were carried out using an iron oxide tape with a coercive force of 900 Oe as a recording medium and at a head-to-tape relative running speed of 5.8 m/s. In measuring F-specific waviness, we record the frequency sweep signal from 0.1 to 10 MHz, and detect the reproduced output using a spectrum analyzer to determine the peaks and valleys in the vicinity of 3 to 7 MHz of the frequency characteristic curve as shown in Figure 5. The output ratio was determined. In the measurement of recording and playback output, 1MHz and 5MHz
A sine wave of 8 MHz was recorded without bias, and the maximum reproduction output value in the reproduction output versus recording current curve was determined.

The data in Table 3 is interpreted as follows. Comparing (2) with the others using (2) as a reference, (2) has the same F-specific waviness, and the reproduction output is slightly higher in the high frequency region. ■
The F characteristic waviness is the same, and the reproduction output is about 1 to 2 dB higher from the low frequency region to the high frequency region. In case (2), the F characteristic waviness is large by about 0.5 dB, but this level of F characteristic waviness is at a level that does not pose a practical problem, and the reproduction output is about 2 dB higher from the low frequency region to the high frequency region. That is, ■, ■, and ■ are equivalent to or higher than standard comparative example ■ in terms of the degree of pseudo gap problem solving and recording/reproducing output, and ■ and ■ are particularly excellent. In cases ① and ②, the F characteristic waviness is extremely large compared to standard comparative example ②, making them impractical.

Based on the above experimental results, the inventor of the present application has determined that ``a ferromagnetic metal thin film is formed on the gap forming surface of at least one magnetic core half of a pair of magnetic core halves made of single-crystal ferrite; In a magnetic head in which a ferromagnetic metal thin film and the other magnetic core half are butted together via a non-magnetic material that forms a magnetic gap, the crystal orientation of the magnetic core half on which the ferromagnetic metal thin film is formed is set to By setting either (2) or (2), superior effects can be obtained in terms of solving the pseudo gap problem and recording/reproducing output compared to setting (2) recommended in the first reference.
This led us to derive the gist of the present invention.

Furthermore, based on FIG. 2 in which the value of the F special waviness in Table 3 is plotted against the value of θ, the inventor of the present application also took into account the continuity of physical quantities, and determined that θ is 0°. ~10
It has been estimated that within the range of 80° to 180°, the F characteristic waviness can be suppressed to below the practical level of about 2 dB.

Note that the above-described effects unique to the present invention do not reflect a synergistic effect due to the fact that the crystal orientations of the single crystal ferrite constituting the core halves on both sides are the same; It is thought that this is due to the superposition of effects in each core half, so even if the single crystal ferrite constituting the core halves on both sides have different crystal orientations, the present invention is applicable to at least one core half. If so, the effects obtained by simply superimposing the effects specific to the present invention on the core half and the characteristics of the other core half should be obtained.

[0024]Although the crystal orientation of the present invention is considered to partially overlap with the crystal orientation claimed in the second reference,
The present invention should be distinguished from the second cited example by the presence or absence of consideration given to the pseudo gap problem and the difference in the magnetic path structure as shown in FIG. 7(b), which affects the recording/reproducing output problem. .

The MIG head to which the present invention is applied is shown in FIG.
The magnetic head is not limited to a magnetic head having an external shape as shown in FIG. 3, but also includes a magnetic head having a recording medium facing surface as shown in FIGS. 3(a), 3(b), and 3(c), for example. Here, FIG. 3(a) shows an MIG head in which a ferromagnetic metal thin film 9a is formed only on one magnetic core half pair 1a, and FIG. 3(b) shows a ferromagnetic metal thin film 9a on both magnetic core half pairs 1a, 1b.
The MIG head 9b has different film thicknesses, and the same (c) shows the ferrite core part of the magnetic core half pair 1a, 1b and the ferromagnetic metal thin film 9.
The MIG head is shown in which the boundary surfaces of a and 9b are non-parallel to the gap mating surface.

[0026]

As described above, the magnetic head according to the present invention has the following advantages: at least the first
The main magnetic path configuration plane recommended in the reference (Japanese Unexamined Patent Publication No. 01-133204) is a {110} crystal plane, and the effect is equivalent to or better than that of the parallel type MIG head whose gap forming plane is a {100} crystal plane. exhibits an effect.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the crystal orientation of a plane constituting the main magnetic path of a magnetic head according to the present invention.

FIG. 2 is a diagram for explaining the amplitude and crystal orientation dependence of F waviness.

FIG. 3 is a plan view showing another embodiment of the recording medium facing surface of the magnetic head of the present invention.

FIG. 4 is an external perspective view of a conventional magnetic head.

FIG. 5 is a diagram showing reproduction output frequency characteristics of a magnetic head.

FIG. 6 is an external perspective view of a magnetic head for explaining a conventional magnetic head and an embodiment of the present invention.

FIG. 7 is a sectional view of a main magnetic path configuration surface of a magnetic head for explaining a conventional magnetic head and an embodiment of the present invention.

[Explanation of symbols]

1a, 1b Magnetic core half 2 Magnetic gap 3a, 3b Ferromagnetic metal thin film 7a, 7b
Heat-resistant thin films 9a, 9b ferromagnetic metal thin films 103a, 10
3b Main magnetic path configuration surface

Claims (5)

[Claims] 1. A ferromagnetic metal thin film is formed on the gap forming surface of at least one of a pair of magnetic core halves made of single-crystal ferrite through a heat-resistant thin film, and the ferromagnetic metal thin film is In a magnetic head in which a magnetic core half is butted against the other magnetic core half through a non-magnetic material that forms a magnetic gap, the crystal plane of the main magnetic path constituting plane of the magnetic core half on which the ferromagnetic metal thin film is formed is abbreviated. {110} and
A vector parallel to the <100> crystal axis in the main magnetic path forming plane and oriented away from the gap forming surface, and a vector parallel to the intersection line between the main magnetic path forming plane and the gap forming surface and approaching the recording medium facing surface. The angle θ with the direction vector is 0° to 10°
or within the range of 80° to 180°. 2. The magnetic head according to claim 1, wherein the angle θ is approximately 0°. 3. The magnetic head according to claim 1, wherein the angle θ is approximately 90°. 4. The magnetic head according to claim 1, wherein the angle θ is approximately 125°. 5. The magnetic head according to claim 1, wherein the angle θ is approximately 145°.